1. Field of the Invention
The present invention relates to a stereoscopic video display control method and control apparatus, more particularly to a method and apparatus for adjusting stereoscopic effects.
2. Description of the Related Art
Three-dimensional video (3D content), which creates a stereoscopic view by displaying separate images for the left and right eyes, is coming into widespread use. When 3D content is created, it is generally adjusted to provide the best stereoscopic view in an assumed viewing environment with standard viewing conditions such as the size of the display screen, the distance from the screen to the viewer, the separation between the viewer's pupils, and the desired stereoscopic depth.
However, individual users' viewing environments tend to vary, and if they depart from the envisioned standard conditions, the stereoscopic effect is degraded. This situation is often encountered in practice. For example, a display screen larger than the standard size creates an exaggerated sense of depth, making the viewer uncomfortable, whereas a screen smaller than the standard size fails to provide sufficient sense of depth. Too short a viewing distance also gives an uncomfortably exaggerated sense of depth, while too long a viewing distance fails to provide sufficient sense of depth.
Individual differences in pupil-to-pupil distance can also produce differences in stereoscopic perception. In addition, people differ in the degree of stereoscopic effect with which they feel comfortable, and in the rapidity with which they tire from continuous stereoscopic viewing. Methods of adjusting stereoscopic effects have therefore been developed and disclosed.
In International Published Patent Application No. WO 2004/084560, Tomita proposes a stereoscopic video photographing and displaying system in which right-eye and left-eye video images are captured by a stereoscopic video imaging unit, transferred via a medium to a stereoscopic video display unit, and displayed. The stereoscopic video imaging unit measures the distance to the subject and sends distance information via the medium together with the video information. The stereoscopic video display unit has an offset setting means that displays the right-eye and left-eye images with different offsets depending on the received distance information and the size of the displayed image.
In Japanese Patent Application Publication No. 2004-180069, Tomita discloses a three-dimensional video displaying device that shifts the right-eye and left-eye images according to information concerning both the stereoscopic video image and the stereoscopic video display device, thereby adjusting the stereoscopic effect of the displayed image.
In Japanese Patent Application Publication No. H09-261691, Tateno discloses a video display system that shifts the display positions of right-eye and left-eye images in the right and left directions by a prescribed distance and displays the shifted images on the screen of a display device that guides the right-eye video image to the viewer's right eye and guides the left-eye video image to the viewer's left eye, thereby generating a virtual image at a distance behind the screen.
In Japanese Patent Application Publication No. H09-271043, Tabata discloses a stereoscopic image display device that reads the parallax of a pair of images displayed separately to the left and right eyes from their separate video signals and varies the effective binocular parallax by horizontally shifting the right-eye and left-eye images according to the instantaneous parallax value.
By horizontally shifting the right-eye and left-eye video images, the conventional art in these disclosures enables adjustment of stereoscopic effects, but with the disadvantage that the left-eye and right-eye video images may be partially shifted off the screen of the display device and lost.
3D content data can be generally classified as 3D broadcast programs supplied via television broadcasts and 3D disc titles supplied on recording media such as Blu-ray discs. 3D broadcast programs are received by a device such as a tuner or set-top box that reconstructs the 3D video signal from the received signal or data and sends the 3D video signal to the 3D display device. 3D disc titles are reproduced by a device, such as a Blu-ray player or a personal computer, that likewise reconstructs the 3D video signal and sends the 3D video signal to the 3D display device. The 3D display device may accordingly be used in combination with either a receiving device or a reproducing device, or with both. The stereoscopic effect then needs to be adjusted across the combination as a whole, but appropriate means for this purpose have been lacking.